The present invention relates generally to optical fiber cables and more particularly to round "high count" fiber optic cables particularly useful for making multiple indoor connections between equipment and hardware that utilize (receive and send) large amounts of data transmitted through the fibers.
Present optical fiber technology typically uses individual or very low count cable (usually less than six fibers) to connect outdoor cables to central office switching equipment and hardware. Such individual or low count cables are inadequate since the amount of indoor connections, fiber counts, and central office racks required is in the hundreds and thousands, depending upon the demand at a given location. As a result, indoor locations have become and typically will become highly congested with cable unless action is taken to reduce the number of cables without reducing the number of optical fibers. In fact, the need is to reduce cable numbers while increasing fiber numbers.
Craftsmanship and the ease of cable handling when connecting fibers to equipment is proportional to (1) the compactness of the cable structure, (2) the accessibility to the fibers within each cable with commonly used craft tools such as strippers that do not nick the fibers, and (3) the adaptability of enclosures and equipment to the cable construction. In addition, supplemental identification techniques must be applied at the location of installation for most of the present cable designs. Hence, for the high count fiber cables, identification of each fiber becomes highly important in the fiber connection and termination process.
And, any new design is obviously more cost effective if existing cabling machinery can be used in making the new cable, as opposed to the use of specialized and dedicated equipment.
Hence, there are real needs for flexible optical fiber cables that can handle substantial amounts of information while remaining compact in size. As explained above, indoor office space is often unavailable for a substantial amount of cabling. When space is found, cables are snaked through and around equipment in a manner that requires a substantial amount of bending so that the fiber optics of the cable are subject to substantial bending and flexing. Any bending of the optics reduces the cables ability to conduct light and therefore can affect the ability to serve its purpose, which is the rapid transmission of substantial amounts of information and data in the form of light pulses.
Anti-buckling means in the fiber optic art, which can also serve as strain relief means for the more delicate optics, are known and have been the subject of patent disclosures, such as U.S. Pat. No. 4,269,024 to Ashpole et al and U.S. Pat. No. 5,101,467 to Bernard. Ashpole et al are concerned with strength (strain relief) members per se, while Bernard shows a cable primarily designed for outside pedestals located near ground level to receive underground cabling. Since the Bernard cable is for outdoor, underground use, the cable has a substantial amount of protective armoring.
In providing a cable for multiple connections to assorted equipment, each fiber within the cable must be accessible in a manner that leaves adjacent fibers intact, i.e., when one subunit or bundle of fibers is connected to one item of equipment, the remaining bundles need to remain in tact for use at adjacent and/or other locations and equipment. In other words, when the outer jacket of a cable is opened to obtain access to subunits of fibers, the remaining subunits need to remain intact so that they can be directed and connected to other related or unrelated equipment. All of this, of course, requires an outer jacketing system that permits easy access to the subunits within the jacket system, and subunits with jackets that maintain the subunits intact when the main, outer jacket is opened.